这是退信的内容
This is the mail system at host mail.sskil.com.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

                   The mail system

<liuzwei_cn@hotmail.com>: host mx1.hotmail.com[65.55.37.88] said: 550 DY-001
    Mail rejected by Windows Live Hotmail for policy reasons. We generally do
    not accept email from dynamic IP's as they are not typically used to
    deliver unauthenticated SMTP e-mail to an Internet mail server.
    http://www.spamhaus.org maintains lists of dynamic and residential IP
    addresses. If you are not an email/network admin please contact your
    E-mail/Internet Service Provider for help. Email/network admins, please
    visit http://postmaster.live.com for email delivery information and support
    (in reply to MAIL FROM command)

<liuzwei_cn@sina.com>: host freemx1.sinamail.sina.com.cn[202.108.3.242] said:
    550 Rejected due to the sending MTA's poor reputation. Please refer
    http://mail.sina.com.cn/help2/rwmail.html (in reply to RCPT TO command)

Reporting-MTA: dns; mail.sskil.com
X-iRedMail-Queue-ID: 52AD013090F
X-iRedMail-Sender: rfc822; www@sskil.com
Arrival-Date: Thu, 16 Jul 2009 17:46:56 +0800 (CST)

Final-Recipient: rfc822; liuzwei_cn@hotmail.com
Original-Recipient: rfc822;liuzwei_cn@hotmail.com
Action: failed
Status: 5.0.0
Remote-MTA: dns; mx1.hotmail.com
Diagnostic-Code: smtp; 550 DY-001 Mail rejected by Windows Live Hotmail for
    policy reasons. We generally do not accept email from dynamic IP's as they
    are not typically used to deliver unauthenticated SMTP e-mail to an
    Internet mail server. http://www.spamhaus.org maintains lists of dynamic
    and residential IP addresses. If you are not an email/network admin please
    contact your E-mail/Internet Service Provider for help. Email/network
    admins, please visit http://postmaster.live.com for email delivery
    information and support

Final-Recipient: rfc822; liuzwei_cn@sina.com
Original-Recipient: rfc822;liuzwei_cn@sina.com
Action: failed
Status: 5.0.0
Remote-MTA: dns; freemx1.sinamail.sina.com.cn
Diagnostic-Code: smtp; 550 Rejected due to the sending MTA's poor reputation.
    Please refer http://mail.sina.com.cn/help2/rwmail.html
这是我的spf记录
[root@mail postfix]# dig -t txt mail.sskil.com

; <<>> DiG 9.3.4-P1 <<>> -t txt mail.sskil.com
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 9266
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2

;; QUESTION SECTION:
;mail.sskil.com.                        IN      TXT

;; ANSWER SECTION:
mail.sskil.com.         1257    IN      TXT     "v=spf1 a ~all"

;; AUTHORITY SECTION:
sskil.com.              99258   IN      NS      ns3.china-enterprise.com.
sskil.com.              99258   IN      NS      ns4.china-enterprise.com.

;; ADDITIONAL SECTION:
ns3.china-enterprise.com. 1243  IN      A       210.51.171.200
ns4.china-enterprise.com. 106585 IN     A       210.51.171.201

;; Query time: 27 msec
;; SERVER: 202.102.134.68#53(202.102.134.68)
;; WHEN: Thu Jul 16 17:49:46 2009
;; MSG SIZE  rcvd: 143
我的邮件系统的是通过路由器映射到内网的一个服务器上的，我公司的域名是由中企动力帮助解析的，可以通过域名访问我的邮件系统，上面的spf记录是通过http://www.xiaohui.com/dev/server/email … config.htm地址来生成的

请看看是否正确，不正确的话应该怎样设定

现在给gmail发邮件没有问题